This invention relates generally to circuitry for providing a constant output current and more particularly to circuitry for providing a constant source current at a high output impedance terminal.
When it is required to provide a constant source current to a load, such as, for example, a capacitor it is desired that the variation in voltage across the load as the capacitor is charged does not cause the constant current supplied thereto to be varied. If the magnitude of current supplied from the constant current source is caused to be varied, due to the change in magnitude of the voltage appearing across the capacitive load, the capacitor would not be charged at a linear rate. However, often it is desired that the charge rate of the capacitor be linear which would be negated if the current from the constant current source were allowed to vary as before mentioned.